This invention relates to a sealing bead intended to be used once only for sealing gaps in installations and machines which are operated at high temperatures, and particularly (but not exclusively) for sealing the gap between a cold billet and a mould in continuous casting machines.
Thus, for example, in a continuous casting plant the mould is closed, prior to commencement of the casting operation, by means of a "head" carried on top of the cold billet in such a way that after casting has commenced the cold billet and the head may be lowered within the mould to carry the frozen part of the continuous casting with them. In order to prevent any escape of molten steel down the sides of the cold billet at the start of the casting operation, the cold billet or its "head " is provided with a seal relative to the walls of the mould. Normally, asbestos cords are used for this purpose, which are pressed into the gap between the mould walls and the cold billet or its head. Owing to the fact that asbestos cord has only a limited degree of cross-sectional deformability however, the resulting seal is not always entirely satisfactory. For this reason it is frequently necessary to employ several layers of asbestos cord. Another disadvantage appertaining to the use of asbestos cord resides in that this material tends to produce dust rubbings which may cause serious damage to health, notably from "asbestosis". Finally, asbestos is a comparatively expensive material and, having once been used at high temperature, it is mostly quite useless for any further application and so becomes an embarrassing waste product.